From my VERY humble expirience with
nanopi M1 + cam500 from friendlyARM
uname -a = Linux nanopim1 3.4.112-sun8i #8 SMP PREEMPT Fri Jul 22 13:36:16 EEST 2016 armv7l armv7l armv7l GNU/Linux
1.move R6 to R5 on cam500 pcb (so making VDDIO 3v, not 1.8V)
2. enable for a while twi2 and check addr 0x3c with i2ctool (in my case works only with VDDIO=3V)
3. edit in script vip_dev0_mname gc2035->ov5640
4. modprobe ov5640, modprobe vfe_v4l2
...
and something like fswebcam -p YUV420P 111.jpg
it seems it works! (somehow